Characterization of a new mechanism of cell wall synthesis regulation in the cholera pathogen
Zusammenfassung der Projektergebnisse
Despite decades of research, the mechanistic details of cell wall synthesis are still poorly understood, especially in organisms other than the model system E. coli. Particularly little is known about how the activities of the cell wall synthases, the Penicillin Binding Proteins (PBPs), are regulated. Vibrio cholerae, the causative agent of Cholera, possesses two main PBPs, PBP1A and PBP1B. It was previously shown that a deletion in PBP1a (∆mrcA) rendered cells sensitive to growth inhibition by endogenously produced D-amino acids (DAA). This strong phenotype provided an ideal genetic system to study the regulation of cell wall synthesis in this important human pathogen. I screened an ordered transposon library for additional mutants that were unable to grow in the presence of DAA and identified mutants in V. cholerae‘s homologue of the PBP1A activator LpoA, as well as a small periplasmic protein of unknown function, which we named CsiV. A deletion mutant in csiV shared many phenotypes with a deletion in PBP1A, i.e. reduced cell wall content, sensitivity to bile, and sphere formation in response to DAAs and cefsulodin. Purified CsiV protein interacted directly with purified LpoA and ∆csiV was synthetic lethal with PBP1B, suggesting that like LpoA, CsiV was required for full activity of PBP1A. DAA- and cefsulodin-mediated growth inhibition of ∆csiV could be ameliorated by deleting a cell wall hydrolase, suggesting that the csiV mutant suffers from an imbalance between cell wall synthesis and degradation. In conclusion, CsiV appears to be a periplasmic modulator of LpoA-mediated PBP1A activation.
Projektbezogene Publikationen (Auswahl)
- (2013): Substrate specificity of an elongation-specific peptidoglycan endopeptidase and its implications for cell wall architecture and growth of Vibrio cholerae, Molecular Microbiology 89(5)
Tobias Dörr, Felipe Cava, Hubert Lam, Brigid M Davis and Matthew K Waldor
- (2014): A Novel Peptidoglycan Binding Protein Crucial for PBP1A-Mediated Cell Wall Biogenesis in Vibrio cholerae, PLOS Genetics 10 (6)
Tobias Dörr, Hubert Lam, Laura Alvarez, Felipe Cava, Brigid M Davis and Matthew K Waldor
(Siehe online unter https://doi.org/10.1371/journal.pgen.1004433) - (2014): Differential requirement for PBP1a and PBP1b in in vivo and in vitro fitness of Vibrio cholerae, Infection and Immunity 82(5)
Tobias Dörr, Andrea Möll, Michael C Chao, Felipe Cava, Hubert Lam, Brigid M Davis and Matthew K Waldor
(Siehe online unter https://doi.org/10.1128/IAI.00012-14)
